This invention relates to an apparatus for separating fiber waste or similar impurities drawn away by suction from fiber processing machines, particularly cleaning machines and cards. The apparatus has a pneumatic conveyor duct which guides the waste-laden air stream into a stationary collecting vessel. The latter has a separating surface for retaining the waste within the collecting vessel, from which the waste may be removed in a downward direction.
A pre-separator (pre-filter) is known which is used for cleaning dust-laden air and which is installed in the de-dusting locations of cotton cleaning assemblies. Such a pre-separator also serves for separating waste in automatic systems for the intermittent waste removal from waste chambers of cotton cleaning machines and carding machines. The pre-separator is essentially a screen drum rotated by a drive motor. The retained fiber material is withdrawn by two cooperating rollers, one of which is provided with a thick foam rubber jacket to ensure that the removal side of the filter housing remains vacuum tight at the fiber outlet regardless of the thickness of the fiber material discharged by the rollers. The smaller of the two delivery rollers which serves as a doffer, is followed by an adjustable brush which cleans the wire mesh of the screen drum. The filter may be accessible through cleaning flaps in the zone of the screen drum underneath the brush and above the delivery rollers. The fiber material discharged by the delivery rollers falls into a waste carriage. In order to avoid damages to the filter, a sensor plate de-energizes the drive motor by means of a limit switch when the waste carriage is filled to capacity. The fiber waste may also be removed by suction and guided to a fiber compactor, a bale press or an installation which processes waste. The air which is filtered out by the screen drum and which still contains fine dust, is then guided to a fine filter through one, two or three pre-filters. It is a disadvantage of this known system that the rotary screen drum is structurally complex.
In another known apparatus, the separating surface is constituted by a planar stationary screening surface which is oriented at an angle of approximately 45.degree. relative to the direction of the waste-laden air stream. It is a disadvantage of such an arrangement that a planar screening surface adversely affects the flow-dynamic properties of the air stream.